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-rw-r--r--fs/efivarfs/vars.c632
1 files changed, 632 insertions, 0 deletions
diff --git a/fs/efivarfs/vars.c b/fs/efivarfs/vars.c
new file mode 100644
index 000000000000..6edc10958ecf
--- /dev/null
+++ b/fs/efivarfs/vars.c
@@ -0,0 +1,632 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Originally from efivars.c
+ *
+ * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
+ * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
+ */
+
+#include <linux/capability.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/smp.h>
+#include <linux/efi.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/ctype.h>
+#include <linux/ucs2_string.h>
+
+#include "internal.h"
+
+MODULE_IMPORT_NS("EFIVAR");
+
+static bool
+validate_device_path(efi_char16_t *var_name, int match, u8 *buffer,
+ unsigned long len)
+{
+ struct efi_generic_dev_path *node;
+ int offset = 0;
+
+ node = (struct efi_generic_dev_path *)buffer;
+
+ if (len < sizeof(*node))
+ return false;
+
+ while (offset <= len - sizeof(*node) &&
+ node->length >= sizeof(*node) &&
+ node->length <= len - offset) {
+ offset += node->length;
+
+ if ((node->type == EFI_DEV_END_PATH ||
+ node->type == EFI_DEV_END_PATH2) &&
+ node->sub_type == EFI_DEV_END_ENTIRE)
+ return true;
+
+ node = (struct efi_generic_dev_path *)(buffer + offset);
+ }
+
+ /*
+ * If we're here then either node->length pointed past the end
+ * of the buffer or we reached the end of the buffer without
+ * finding a device path end node.
+ */
+ return false;
+}
+
+static bool
+validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer,
+ unsigned long len)
+{
+ /* An array of 16-bit integers */
+ if ((len % 2) != 0)
+ return false;
+
+ return true;
+}
+
+static bool
+validate_load_option(efi_char16_t *var_name, int match, u8 *buffer,
+ unsigned long len)
+{
+ u16 filepathlength;
+ int i, desclength = 0, namelen;
+
+ namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN);
+
+ /* Either "Boot" or "Driver" followed by four digits of hex */
+ for (i = match; i < match+4; i++) {
+ if (var_name[i] > 127 ||
+ hex_to_bin(var_name[i] & 0xff) < 0)
+ return true;
+ }
+
+ /* Reject it if there's 4 digits of hex and then further content */
+ if (namelen > match + 4)
+ return false;
+
+ /* A valid entry must be at least 8 bytes */
+ if (len < 8)
+ return false;
+
+ filepathlength = buffer[4] | buffer[5] << 8;
+
+ /*
+ * There's no stored length for the description, so it has to be
+ * found by hand
+ */
+ desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
+
+ /* Each boot entry must have a descriptor */
+ if (!desclength)
+ return false;
+
+ /*
+ * If the sum of the length of the description, the claimed filepath
+ * length and the original header are greater than the length of the
+ * variable, it's malformed
+ */
+ if ((desclength + filepathlength + 6) > len)
+ return false;
+
+ /*
+ * And, finally, check the filepath
+ */
+ return validate_device_path(var_name, match, buffer + desclength + 6,
+ filepathlength);
+}
+
+static bool
+validate_uint16(efi_char16_t *var_name, int match, u8 *buffer,
+ unsigned long len)
+{
+ /* A single 16-bit integer */
+ if (len != 2)
+ return false;
+
+ return true;
+}
+
+static bool
+validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer,
+ unsigned long len)
+{
+ int i;
+
+ for (i = 0; i < len; i++) {
+ if (buffer[i] > 127)
+ return false;
+
+ if (buffer[i] == 0)
+ return true;
+ }
+
+ return false;
+}
+
+struct variable_validate {
+ efi_guid_t vendor;
+ char *name;
+ bool (*validate)(efi_char16_t *var_name, int match, u8 *data,
+ unsigned long len);
+};
+
+/*
+ * This is the list of variables we need to validate, as well as the
+ * whitelist for what we think is safe not to default to immutable.
+ *
+ * If it has a validate() method that's not NULL, it'll go into the
+ * validation routine. If not, it is assumed valid, but still used for
+ * whitelisting.
+ *
+ * Note that it's sorted by {vendor,name}, but globbed names must come after
+ * any other name with the same prefix.
+ */
+static const struct variable_validate variable_validate[] = {
+ { EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 },
+ { EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order },
+ { EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option },
+ { EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order },
+ { EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option },
+ { EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path },
+ { EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path },
+ { EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path },
+ { EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path },
+ { EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path },
+ { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path },
+ { EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string },
+ { EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL },
+ { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string },
+ { EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 },
+ { LINUX_EFI_CRASH_GUID, "*", NULL },
+ { NULL_GUID, "", NULL },
+};
+
+/*
+ * Check if @var_name matches the pattern given in @match_name.
+ *
+ * @var_name: an array of @len non-NUL characters.
+ * @match_name: a NUL-terminated pattern string, optionally ending in "*". A
+ * final "*" character matches any trailing characters @var_name,
+ * including the case when there are none left in @var_name.
+ * @match: on output, the number of non-wildcard characters in @match_name
+ * that @var_name matches, regardless of the return value.
+ * @return: whether @var_name fully matches @match_name.
+ */
+static bool
+variable_matches(const char *var_name, size_t len, const char *match_name,
+ int *match)
+{
+ for (*match = 0; ; (*match)++) {
+ char c = match_name[*match];
+
+ switch (c) {
+ case '*':
+ /* Wildcard in @match_name means we've matched. */
+ return true;
+
+ case '\0':
+ /* @match_name has ended. Has @var_name too? */
+ return (*match == len);
+
+ default:
+ /*
+ * We've reached a non-wildcard char in @match_name.
+ * Continue only if there's an identical character in
+ * @var_name.
+ */
+ if (*match < len && c == var_name[*match])
+ continue;
+ return false;
+ }
+ }
+}
+
+char *
+efivar_get_utf8name(const efi_char16_t *name16, efi_guid_t *vendor)
+{
+ int len = ucs2_utf8size(name16);
+ char *name;
+
+ /* name, plus '-', plus GUID, plus NUL*/
+ name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
+ if (!name)
+ return NULL;
+
+ ucs2_as_utf8(name, name16, len);
+
+ name[len] = '-';
+
+ efi_guid_to_str(vendor, name + len + 1);
+
+ name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
+
+ /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
+ strreplace(name, '/', '!');
+
+ return name;
+}
+
+bool
+efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
+ unsigned long data_size)
+{
+ int i;
+ unsigned long utf8_size;
+ u8 *utf8_name;
+
+ utf8_size = ucs2_utf8size(var_name);
+ utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL);
+ if (!utf8_name)
+ return false;
+
+ ucs2_as_utf8(utf8_name, var_name, utf8_size);
+ utf8_name[utf8_size] = '\0';
+
+ for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
+ const char *name = variable_validate[i].name;
+ int match = 0;
+
+ if (efi_guidcmp(vendor, variable_validate[i].vendor))
+ continue;
+
+ if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
+ if (variable_validate[i].validate == NULL)
+ break;
+ kfree(utf8_name);
+ return variable_validate[i].validate(var_name, match,
+ data, data_size);
+ }
+ }
+ kfree(utf8_name);
+ return true;
+}
+
+bool
+efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
+ size_t len)
+{
+ int i;
+ bool found = false;
+ int match = 0;
+
+ /*
+ * Check if our variable is in the validated variables list
+ */
+ for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
+ if (efi_guidcmp(variable_validate[i].vendor, vendor))
+ continue;
+
+ if (variable_matches(var_name, len,
+ variable_validate[i].name, &match)) {
+ found = true;
+ break;
+ }
+ }
+
+ /*
+ * If it's in our list, it is removable.
+ */
+ return found;
+}
+
+/*
+ * Returns the size of variable_name, in bytes, including the
+ * terminating NULL character, or variable_name_size if no NULL
+ * character is found among the first variable_name_size bytes.
+ */
+static unsigned long var_name_strnsize(efi_char16_t *variable_name,
+ unsigned long variable_name_size)
+{
+ unsigned long len;
+ efi_char16_t c;
+
+ /*
+ * The variable name is, by definition, a NULL-terminated
+ * string, so make absolutely sure that variable_name_size is
+ * the value we expect it to be. If not, return the real size.
+ */
+ for (len = 2; len <= variable_name_size; len += sizeof(c)) {
+ c = variable_name[(len / sizeof(c)) - 1];
+ if (!c)
+ break;
+ }
+
+ return min(len, variable_name_size);
+}
+
+/*
+ * Print a warning when duplicate EFI variables are encountered and
+ * disable the sysfs workqueue since the firmware is buggy.
+ */
+static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
+ unsigned long len16)
+{
+ size_t i, len8 = len16 / sizeof(efi_char16_t);
+ char *str8;
+
+ str8 = kzalloc(len8, GFP_KERNEL);
+ if (!str8)
+ return;
+
+ for (i = 0; i < len8; i++)
+ str8[i] = str16[i];
+
+ printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
+ str8, vendor_guid);
+ kfree(str8);
+}
+
+/**
+ * efivar_init - build the initial list of EFI variables
+ * @func: callback function to invoke for every variable
+ * @data: function-specific data to pass to @func
+ * @duplicate_check: fail if a duplicate variable is found
+ *
+ * Get every EFI variable from the firmware and invoke @func. @func
+ * should populate the initial dentry and inode tree.
+ *
+ * Returns 0 on success, or a kernel error code on failure.
+ */
+int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
+ void *data, bool duplicate_check)
+{
+ unsigned long variable_name_size = 512;
+ efi_char16_t *variable_name;
+ efi_status_t status;
+ efi_guid_t vendor_guid;
+ int err = 0;
+
+ variable_name = kzalloc(variable_name_size, GFP_KERNEL);
+ if (!variable_name) {
+ printk(KERN_ERR "efivars: Memory allocation failed.\n");
+ return -ENOMEM;
+ }
+
+ err = efivar_lock();
+ if (err)
+ goto free;
+
+ /*
+ * A small set of old UEFI implementations reject sizes
+ * above a certain threshold, the lowest seen in the wild
+ * is 512.
+ */
+
+ do {
+ variable_name_size = 512;
+ BUILD_BUG_ON(EFI_VAR_NAME_LEN < 512);
+
+ status = efivar_get_next_variable(&variable_name_size,
+ variable_name,
+ &vendor_guid);
+ switch (status) {
+ case EFI_SUCCESS:
+ variable_name_size = var_name_strnsize(variable_name,
+ variable_name_size);
+
+ /*
+ * Some firmware implementations return the
+ * same variable name on multiple calls to
+ * get_next_variable(). Terminate the loop
+ * immediately as there is no guarantee that
+ * we'll ever see a different variable name,
+ * and may end up looping here forever.
+ */
+ if (duplicate_check &&
+ efivarfs_variable_is_present(variable_name,
+ &vendor_guid, data)) {
+ dup_variable_bug(variable_name, &vendor_guid,
+ variable_name_size);
+ status = EFI_NOT_FOUND;
+ } else {
+ err = func(variable_name, vendor_guid,
+ variable_name_size, data);
+ if (err)
+ status = EFI_NOT_FOUND;
+ }
+ break;
+ case EFI_UNSUPPORTED:
+ err = -EOPNOTSUPP;
+ status = EFI_NOT_FOUND;
+ break;
+ case EFI_NOT_FOUND:
+ break;
+ case EFI_BUFFER_TOO_SMALL:
+ pr_warn("efivars: Variable name size exceeds maximum (%lu > 512)\n",
+ variable_name_size);
+ status = EFI_NOT_FOUND;
+ break;
+ default:
+ pr_warn("efivars: get_next_variable: status=%lx\n", status);
+ status = EFI_NOT_FOUND;
+ break;
+ }
+
+ } while (status != EFI_NOT_FOUND);
+
+ efivar_unlock();
+free:
+ kfree(variable_name);
+
+ return err;
+}
+
+/**
+ * efivar_entry_delete - delete variable
+ * @entry: entry containing variable to delete
+ *
+ * Delete the variable from the firmware. It is the caller's
+ * responsibility to free @entry (by deleting the dentry/inode) once
+ * we return.
+ *
+ * Returns 0 on success, -EINTR if we can't grab the semaphore,
+ * converted EFI status code if set_variable() fails.
+ */
+int efivar_entry_delete(struct efivar_entry *entry)
+{
+ efi_status_t status;
+ int err;
+
+ err = efivar_lock();
+ if (err)
+ return err;
+
+ status = efivar_set_variable_locked(entry->var.VariableName,
+ &entry->var.VendorGuid,
+ 0, 0, NULL, false);
+ efivar_unlock();
+ if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND))
+ return efi_status_to_err(status);
+
+ return 0;
+}
+
+/**
+ * efivar_entry_size - obtain the size of a variable
+ * @entry: entry for this variable
+ * @size: location to store the variable's size
+ */
+int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
+{
+ efi_status_t status;
+ int err;
+
+ *size = 0;
+
+ err = efivar_lock();
+ if (err)
+ return err;
+
+ status = efivar_get_variable(entry->var.VariableName,
+ &entry->var.VendorGuid, NULL, size, NULL);
+ efivar_unlock();
+
+ if (status != EFI_BUFFER_TOO_SMALL)
+ return efi_status_to_err(status);
+
+ return 0;
+}
+
+/**
+ * __efivar_entry_get - call get_variable()
+ * @entry: read data for this variable
+ * @attributes: variable attributes
+ * @size: size of @data buffer
+ * @data: buffer to store variable data
+ *
+ * The caller MUST call efivar_entry_iter_begin() and
+ * efivar_entry_iter_end() before and after the invocation of this
+ * function, respectively.
+ */
+int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
+ unsigned long *size, void *data)
+{
+ efi_status_t status;
+
+ status = efivar_get_variable(entry->var.VariableName,
+ &entry->var.VendorGuid,
+ attributes, size, data);
+
+ return efi_status_to_err(status);
+}
+
+/**
+ * efivar_entry_get - call get_variable()
+ * @entry: read data for this variable
+ * @attributes: variable attributes
+ * @size: size of @data buffer
+ * @data: buffer to store variable data
+ */
+int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
+ unsigned long *size, void *data)
+{
+ int err;
+
+ err = efivar_lock();
+ if (err)
+ return err;
+ err = __efivar_entry_get(entry, attributes, size, data);
+ efivar_unlock();
+
+ return 0;
+}
+
+/**
+ * efivar_entry_set_get_size - call set_variable() and get new size (atomic)
+ * @entry: entry containing variable to set and get
+ * @attributes: attributes of variable to be written
+ * @size: size of data buffer
+ * @data: buffer containing data to write
+ * @set: did the set_variable() call succeed?
+ *
+ * This is a pretty special (complex) function. See efivarfs_file_write().
+ *
+ * Atomically call set_variable() for @entry and if the call is
+ * successful, return the new size of the variable from get_variable()
+ * in @size. The success of set_variable() is indicated by @set.
+ *
+ * Returns 0 on success, -EINVAL if the variable data is invalid,
+ * -ENOSPC if the firmware does not have enough available space, or a
+ * converted EFI status code if either of set_variable() or
+ * get_variable() fail.
+ *
+ * If the EFI variable does not exist when calling set_variable()
+ * (EFI_NOT_FOUND).
+ */
+int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
+ unsigned long *size, void *data, bool *set)
+{
+ efi_char16_t *name = entry->var.VariableName;
+ efi_guid_t *vendor = &entry->var.VendorGuid;
+ efi_status_t status;
+ int err;
+
+ *set = false;
+
+ if (efivar_validate(*vendor, name, data, *size) == false)
+ return -EINVAL;
+
+ /*
+ * The lock here protects the get_variable call and the
+ * conditional set_variable call
+ */
+ err = efivar_lock();
+ if (err)
+ return err;
+
+ status = efivar_set_variable_locked(name, vendor, attributes, *size,
+ data, false);
+ if (status != EFI_SUCCESS) {
+ err = efi_status_to_err(status);
+ goto out;
+ }
+
+ *set = true;
+
+ /*
+ * Writing to the variable may have caused a change in size (which
+ * could either be an append or an overwrite), or the variable to be
+ * deleted. Perform a GetVariable() so we can tell what actually
+ * happened.
+ */
+ *size = 0;
+ status = efivar_get_variable(entry->var.VariableName,
+ &entry->var.VendorGuid,
+ NULL, size, NULL);
+
+ efivar_unlock();
+
+ if (status && status != EFI_BUFFER_TOO_SMALL)
+ return efi_status_to_err(status);
+
+ return 0;
+
+out:
+ efivar_unlock();
+ return err;
+
+}
generated by cgit (git 2.34.1) at 2025-12-25 01:21:25 +0000